Polyphenyl ether lubricating compositions

ABSTRACT

COMPOSITION COMPRISING POLYPHENYL ETHERS OR MIXTURES THEREOF AND PHENOXYPHENYLPHOSPHINIC ACIDS EXHIBIT IMPROVED LURBICATING PROPERTIES OVER WIDE TEMPERATURE RANGES.

United States Patent Ofice 3,706,668 Patented Dec. 19, 1972 ABSTRACT OFTHE DISCLOSURE Composition comprising polyphenyl ethers or mixturesthereof and phenoxyphenylphosphinic acids exhibit improved lurbicatingproperties over wide temperature ranges.

This invention relates to improved lubricating compositions comprisingpolyphenyl ethers and mixtures thereof containing from 3 to 8 aromaticgroups and a phenoxyphenylphosphinic acid as a lubricating additive.

Polyphenyl ethers have found wide application as functional fluids inview of their excellent thermal stability and lubricity. For examplethey have been found to be valuable as hydraulic fluids and aslubricants in motor operation, particularly in jet engines.

Development of synthetic base stocks such as the polyphenyl ether hasprovided lubricant fluids which are useful at elevated temperature suchas 400 to 500 F. It is known that one of the aspects in Which thepolyphenyl ether base stocks are considered deficient is in theirlubricating characteristics. These lubricating characteristics includethe load-carrying abilities and wear properties, especially underconditions of high pressures and temperatures reached in the advancedesign aircraft engines. Thus there is a demand for polyphenyl ethershaving improved lubricity properties.

An object of the present invention is to provide base stock compositionsemploying polyphenyl ethers or mixtures thereof that exhibit improvedlubricating properties.

These and other objects will become evident upon consideration of thefollowing specification and example.

It has now been found that compositions comprising a major amount of apolyphenyl ether base stock and a lubricating additive amount of aphenoxyphenylphosphinic acid, have unusual ability to lubricate underhigh loads at high temperatures.

Any of the well known polyphenyl ether base stocks can be used inaccordance with this invention. However, the polyphenyl ether basestocks represented by a member selected from the following formulae arepreferred.

such as 3,3-bisphenoxy biphenyl,

where m is 2, 3, or 4 such as (III) such as 1,3,4-triphenoxybenezne,

(IV) and mixtures thereof.

Mixtures of polyphenyl ethers in which the nonterminal phenylene ringsare linked through oxygen atoms in the meta and/ or parapositions, havebeen found to be particularly suitable. An example of such polyphenylether compositions are those containing, in percent by weight, fromabout 0 to 6% of o-bis(m-phenoxyphenoxy)benzene (1), about 40 to ofm-bis(m-phenoxyphenoxy)benzene (2), about 0 to 40% ofm-[(m-phenoxyphenoxy) (p-phenoxyphenoxy)]benzene (3), about 0 to 12% ofpbis(m-phenoxyphenoxy)benzene (4) about 0 to 10% of p-[p-phenoxyphenoxy) (m-phenoxyphenoxy) ]benzene (5), and about 0 to 6% ofm-bis(p-phenoxyphenoxy)benzene (6). Typical compositions of suchmixtures are listed below. The number of parentheses refers to thecompound mentioned above having the same number thereafter.

Mixtures, percent by weight of components A B C D Component:

wherein R and R are alkyl of not more than 4 carbon atoms, haloalkyl ofnot more than 4 carbon atoms and 3 halogen (Cl, Br and F) atoms, halogen(Cl, Br and F) hydroxyl or phenyl, and n and a are integers from 0 to 3.

Representative groups for R and R in the above formulae include alkylsuch as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl and t-butyland haloalkyl such as chloromethyl, brornomethyl, chloroethyl,bromoethyl, trichloromethyl, tribromomethyl, dichloroethyl,chloro-npropyl, bromo-n-propyl, bromo-n-butyl, bromo-tert-butyl,1,3,3-trich1orobutyl and 1,3,3-tribromobutyl.

Phenoxyphenylphosphinic acids represented by the above formula include,for example,

p-phenoxyphenylphosphinic acid, o-phenoxyphenylphosphinic acid,p-(p-methylphenoxy)phenylphosphinic acid, o-(p-methylphenoxy)phenylphosphinic acid,p-(o-methylphenoxy)phenylphosphinic acid, p- (p-ethylphenoxy)phenylphosphinic acid, p-(o-ethylphenoxy) phenylphosphinic acid,o-(o-ethylphenoxy)phenylphosphinic acid,p-(p-butylphenoxy)phenylphosphinic acid, p-(p-chlorophenoxy)phenylphosphinic acid,o-(m-chlorophenoxy)phenylphosphinic acid,p-(p-phenylphenoxy)phenylphosphinic acid,-(p-phenylphenoxy)phenylphosphinic acid,p-(o-hydroxyphenoxy)phenylphosphinic acid,p-(m-bromophenoxy)phenylphosphinic acid, p-(p-hydroxyphenyl)phenylphosphinic acid,o-(m-phenylphenoxy)phenylphosphinic acid,o-(p-methylphenoxy)m-methylphenylphosphinic acid, o- (p-methylphenoxy)-m-chloromethylphenylphosphinic acid,p-(p-methylphenoxy)-m-trifluoromethylphenylphosphinic acid,p-(o-butylphenoxy)-o-trifluoromethylphenylphosphinic acid,m-(o-phenylphenoxy)-p-methylphenylphosphinic acid,m-(o-methylphenoxy)-o-butylphenylphosphinic acid,m-(o-chloromethylphenoxy)-o-methylphenylphosphinic acid,0-(m-methylphenoxy)-p-trifiuoromethylphenylphosphinic acid, o-(m-hydroxyphenoxy)-p-hydroxyphenylphosphinic acid,o-(m-phenylphenoxy)-m-chloromethylphenylphosphinic acid,p-(m-phenylphenoxy)-m-hydroxyphenylphosphinic acid.

The improvement in lubricity characteristics achieved by the addition ofthe phenoxyphenylphosphinic acids to the polyphenyl ether base fluid isunusual and surprising. The compositions are particularly useful forsteel on steel lubrimtion.

The compositions of this invention contain a major amount of thepolyphenyl ether base stock, i.e., at least 50% by weight of the totalcomposition comprises a polyphenyl ether. It is preferred that at least60% by weight of the composition be a polyphenyl ether base stock andeven more preferred that at least 85% by weight of the total compositioncomprise a polyphenyl ether.

The compositions of this invention can also contain from 0.01 to byweight of the total composition of a dialkyl hydrogen phosphite extremepressure additive. The dialkyl hydrogen phosphites useful are thosewherein the alkyl groups contain from 1 to 12 carbon atoms. These alkylgroups are, for example, methyl, ethyl, propyl, isopropyl, butyl,sec-butyl, t-butyl, hexyl, decyl isodecyl, dodecyl and the like.

The phenoxyphenylphosphinic acids useful in this invention are preparedby interaction of a phosphine of the formula wherein R, R n and a are asdefined above with ethyl alcohol and water.

The interaction is carried out in the absence of a solvent by heatingthe admixture of the three components at temperatures up to andincluding reflux temperature. Pressure is not critical andsubatmospheric, atmospheric and superatmospheric pressures can beemployed. It is generally preferred to slowly add the phosphine to theethyl alcohol and then to add the water to the admixture of phosphineand ethyl alcohol prior to heating. After reaction is complete,generally a period not exceeding more than ten or fifteen minutes, theexcess ethyl alcohol and water are removed by azeotropic distillationwith an azeotroping agent such as benzene.

The separation of the desired phosphinic acid from the azeotroping agentis readily accomplished by conventional means well known to the art. Forexample, distillation, fractional distillation under reduced pressure,selective extraction, fractional distillation using a carrier gas, filmdistillation, evaporation, elution, or any suitable combination of thesemethods.

Dichlorophenoxyphenylphosphines can be prepared by Friedel-Craftcondensation of diphenyl ethers with phosphorus trichloride inaccordance with the procedure set forth in Organic Synthesis, 31, p. 88(1951).

The following examples serve to further illustrate the invention. Allparts are parts by weight unless otherwise expressly set forth.

EXAMPLE 1 This example describes the preparation ofp-phenoxyphenylphosphinic acid. One part ofdichloro-p-phenoxyphenylphosphine (B.P. 138-143 C./0.5 mm. Hg) is slowlyadded to five parts of absolute ethyl alcohol in a suitable vessel andthen two parts of water are added to the alcohol phosphine admixturewith continuous stirring. The resulting mixture is heated at reflux forabout five minutes. Evaporation of alcohol and water provides an oilysubstance. Residual alcohol and water are removed from the oilysubstance by azeotropic distillation using benzene as the azeotropingagent. The benzene is removed from the acid by evaporation producing anoil which slowly crystallizes. The crystals are dried and subjected torecrystallization from benzene and from an admixture of 70% benzene and30% petroleum ether (B.P. 30-75 C.). The productp-phenoxyphenylphosphinic acid has a melting point of 96.5-98 C. and isconfirmed by N.M.R.

EXAMPLE 2 A polyphenylether lubricant composition is prepared bycombining p-phenoxyphenylphosphinic acid (0.10 gram) with 100 grams of apolyphenyl ether of the following composition:

Percent m-Bis(mphenoxyphenoxy)benzene 65.0m-(m-Phenoxyphenoxy)phenyl-p-phenoxyphenyletherm-Bis(p-phenoxyphenoxy)benzene 3 kg. load 1 r.p.m. Room temperature to700 F.

The speed of rotation is very low, namely one r.p.m. This equals 0.88inch/minute. This is done for two reasons. It insures boundaryconditions, i.e., metal to metal contact. It also eliminates metal skintemperature flashes which can occur at high speeds. Thus the bulk oiltemperature is equivalent to the metal surface temperature. Under theseconditions wear is negligible and friction is used to followlubrication. After covering the ball and disc with the test oil, theinitial friction is recorded. The test sample is then heated at 700 F.with continuous recording of the friction. This gives a boundaryfrictiontemperature profile for the experimental fiuid over thistemperature range.

The p-phenoxyphenylphosphinic acid/polyphenyl ether composition of thisexample was tested by this procedure on MS tool steel. The base stockwas also tested for control purposes. The measured coefficient offriction of the composition of this example was substantially lower thanthe measured coeflficient of friction for the base fluid over thetemperature range from 300 F. to 700 F. and particularly from 350 F. to430 F. and from 500 F. and 700 F.

I claim:

1. Composition comprising a major amount of a polyphenyl ether and fromabout 0.01 to about 0.5% by weight of a phenoxyphenylphosphinic acid ofthe formula wherein R and R are alkyl of not more than 4 carbon atoms,haloalkyl of not more than 4 carbon atoms and 3 halogen atoms, halogen,hydroxyl or phenyl and n and a are integers from 0 to 3. 2. Compositionof claim 1 wherein the phenoxyphenylphosphinic acid is present inamounts of from about 0.05 to about 0.2% by weight.

3. Composition of claim 1 wherein the phenoxyphenylphosphinic acid isp-phenoxyphenylphosphinic acid.

4. Composition of claim 1 wherein the phenoxyphenylphosphinic acid iso-phenoxyphenylphosphinic acid.

5. Composition of claim 1 wherein the phenoxyphenylphosphinic acid ism-phenoxyphenylphosphinic acid.

6. Composition of claim 1 wherein R and R are alkyl and n and a are one.

7. Composition of claim 1 wherein R is alkyl, n is one and a is zero.

8. Composition of claim 1 wherein R is phenyl, n is one, and a is zero.

9. Composition of claim 1 wherein R is hydroxyl, n is one and a is zero.

10. Composition of claim 5 wherein R and R are methyl.

References Cited UNITED STATES PATENTS 2,614,990 10/1952 Harman et a1252-499 2,913,415 11/1959 Schmitz 252-49.8 X

FOREIGN PATENTS 606,672 10/1960 Canada 25249.9'

851,651 10/1960 Great Britain 252-52 R DANIEL E. WYMAN, Primary ExaminerW. H. CANNON, Assistant Examiner US. Cl. X.R.

